9.1.0 changelog (#2940) (#2941)

Co-authored-by: Josh Mock <joshua.mock@elastic.co>

Author: github-actions[bot]

docs/release-notes/index.md

@@ -20,25 +20,35 @@ To check for security updates, go to [Security announcements for the Elastic sta
 % ### Fixes [elasticsearch-javascript-client-next-fixes]
 % \*
 
+## 9.1.0 [elasticsearch-javascript-client-9.1.0-release-notes]
+
+### Features and enhancements [elasticsearch-javascript-client-9.1.0-features-enhancements]
+
+- **Compatibility with Elasticsearch 9.1:** All changes and additions to Elasticsearch APIs for its 9.1 release are reflected in this release.
+
+### Fixes [elasticsearch-javascript-client-9.1.0-fixes]
+
+- **Deep merge nested options on client instantiation:** If custom values for `redaction` and `headers` options were set by the user during `Client` instantiation, nested default values would be dropped rather than deep-merged. This has been fixed.
+
 ## 9.0.3
 
 ### Fixes [elasticsearch-javascript-client-9.0.3-fixes]
 
-**Improved compatibility with Elasticsearch 9.0:** Several fixes and improvements have been made to APIs and TypeScript type definitions to better reflect the Elasticsearch 9.0 specification.
+- **Improved compatibility with Elasticsearch 9.0:** Several fixes and improvements have been made to APIs and TypeScript type definitions to better reflect the Elasticsearch 9.0 specification.
 
 ## 9.0.2
 
 ### Fixes [elasticsearch-javascript-client-9.0.2-fixes]
 
-**Remove dangling references to `typesWithBodyKey`:** the `typesWithBodyKey.ts` file and `estypesWithBody` export were removed in 9.0.0 but were still being referenced in the `index.d.ts` file that declares TypeScript types. This reference has been removed.
+- **Remove dangling references to `typesWithBodyKey`:** the `typesWithBodyKey.ts` file and `estypesWithBody` export were removed in 9.0.0 but were still being referenced in the `index.d.ts` file that declares TypeScript types. This reference has been removed.
 
 ## 9.0.1
 
 ### Fixes [elasticsearch-javascript-client-9.0.1-fixes]
 
-**Reinstate `nodeFilter` and node `roles` feature:** The docs note a `nodeFilter` option on the client that will, by default, filter the nodes based on any `roles` values that are set at instantiation. At some point, this functionality was partially disabled. This brings the feature back, ensuring that it matches what the documentation has said it does all along.
+- **Reinstate `nodeFilter` and node `roles` feature:** The docs note a `nodeFilter` option on the client that will, by default, filter the nodes based on any `roles` values that are set at instantiation. At some point, this functionality was partially disabled. This brings the feature back, ensuring that it matches what the documentation has said it does all along.
 
-**Ensure Apache Arrow ES|QL helper uses async iterator:** the [`esql.toArrowReader()` helper function](/reference/client-helpers.md#_toarrowreader) was trying to return `RecordBatchStreamReader`—a synchronous iterator—despite the fact that the `apache-arrow` package was, in most cases, automatically coercing it to `AsyncRecordBatchStreamReader`, its asynchronous counterpart. It now is always returned as an async iterator.
+- **Ensure Apache Arrow ES|QL helper uses async iterator:** the [`esql.toArrowReader()` helper function](/reference/client-helpers.md#_toarrowreader) was trying to return `RecordBatchStreamReader`—a synchronous iterator—despite the fact that the `apache-arrow` package was, in most cases, automatically coercing it to `AsyncRecordBatchStreamReader`, its asynchronous counterpart. It now is always returned as an async iterator.
 
 ## 9.0.0 [elasticsearch-javascript-client-9.0.0-release-notes]